Fractal analysis of pore characteristics and their impacts on methane adsorption of coals from Northern China

摘要

To better understand the pore characteristics of coal and their impacts on methane adsorption, we have conducted fractal analyses on eight coal samples from Northern China. Results show that the two fractal dimensions have different impact on methane adsorption: D-1 has a positive effect on Langmuir volume while D-2 has an opposite effect. Langmuir pressure P-L decreases with increasing D-1, however, there is no relationship between P-L and D-2. The relationships between pore size distribution and methane adsorption show that both transitional pores and micropores are favourable for methane adsorption reflected in the positive effects on Langmuir volume V-L while only micropores especially pores with diameter smaller than 1.5 nm have significant influence on Langmuir pressure P-L. The relationship between coal rank and Langmuir volume V-L is characterised by a U-shaped curve, with minimum values at medium coal rank (1.0 < R-o,R-max < 1.5), whereas the Langmuir pressure P-L decreases with increasing coal rank.